Telephone apparatus



Ue@ i, w25- g@ L. SCHMIDT TELEPHONE APPARATUS Filed JamE 31, 1923 INVENTOR MA ATTORNEY CFI Patented Dec. l, lgti,

STATE PATENT FFIQE.

LAMBERT SCHMIDT, 0F BROOKLYN, NEW YORK, ASSIGNGR T0 RADIOTIVE CORPORA- TION, OF BROOKLYN, NEW YRK.

TELEPHGNE APPARATUS.

Application filed January 31, 1923.

To all 'whom t may concern:

Be it known that I, Lanceur ticrriuinr, a citizen of the United States, and a resident et Brooklyn, county oit Kings, and State of New York, have invented cert-ain new and useful Improvements in Telephone Apparatus, of which the following is a specilication.

This invention relates to telephone apparatus and more particularly to a loud speaking receiver especially designed for use in connection with apparatus employed tor the purpose ot establishing wireless telephonie communication.

In Patent No. 1,452,850, issued April 24., 1928, l have illustrated and described a megnetic structure or' this general character.

lilhile the device disclosed by said patent is very sensitive to variations in polarity ot' the alternating currents passing through the translating coil oi the telephone magnet, it has been found that in certain respects better results may be obtained by means ot the improved device which I shall presently describe, particularly as regards clearness of the sound tones which are produced by vibrations of a sound diaphragm which is connected with the magnet armature.

ln my prior construction, as in numerous other types of magnet telephones heretofore employed, the 'fulcrum for the vibratory armature is located at one side ot or out oit' line with the axis ot the arniature. It is evident, "therefore, that the extent of vibratory movement of 'the ends ot the armature between the opposed magnet poles will be unequal. Accordingly, it is my present purpose, to devise a magnetic structure .tor such telephone apparatus wherein the 'ulcrum of the armature will be located exactly in the line of its axis, and at a point which is midway between the opposite ends of the armature disposed between the spaced shoes or branches of the opposed magnet poles. By means ot such construction, l have simpliiied the magnetic structure to a marked extent, appreciably reducing its manufacturing cost and at the same time have succeeded in obtaining noticeably improved results in the loudness and clearness of the tone, in comparison with the results which it is possible to produce by means ci' such devices heretofore known to the art.

In a more specific aspect, my invention coniprehends the provision of an armature Serial No. 615,981.

ottubular form and a vibratory support for said armature coaxially related therewith and having a part fixed in one end ot the tubular armature whereby said magnet and its support are connected as a unit for arrangement through the bore of the translating coil spool. The support is -formed with a reduced resiliently yielding iulcruin portion enclosed by the tubular armature and located centrally between its ends and ei:- actly in the line ot the arn'iature axis. rllhus, upon change in direction ot the alternating currents passing through the coil and variations in the magnetic fluir, the tubular armature will vibrate in the core ot the spool, and owing to the tact that the fulcrumed point is exactly centered within this tubular armature, the' extent of vibratory movement of the armature at its ends between the pole shoes will be exactly equal.

With the above and other objects in view, the invention consists in the improved magnetic structure for telephone apparatus and in th-e form, construction and relative arrangement of its several parts as will be hereine after more fully described, illustrated in the accompanying drawing and subsequently incorporated in the subjoined claims.

In the drawing wherein I have illustrated one desirable and practical embodiment ci the invention and in which similar re'lerence characters designate corresponding parts throughout the several views:

Figure 1 is a rear elevation, the casing being removed to illustrate one embodiment ot the magnetic structure;

Figure 2 is a section taken on the line 2 2 ot Figure 1;

Figure 3 is a view looking` in a direction at right angles to Figure l;

Figure Ll is an enlarged detail section taken on the line 4-4 of Figure 3;

Figure 5 is an enlarged perspective view oi" the armature and its vibratory support, the armature being shown in section; and

Figures 6 and 7 are detail perspective views showing several modified iiorms of the armature support.

las in the patent above referred to, in the embodiment ot my present invention, which l have selected for purposes of illustration, there is provided a pern'ianent magnet 5 ot conventional U-shaped iorm. To the inner opposed faces ot the parallel legs of this permanent magnet the pole pieces 6 and 7 Aeter, a short end portion respectively, are suitably secured, as by means ot the screws 8. 'lhese pole pieces at their relatively opposite ends are lormed with tlanges S) and 10 respectively, projecting inwardly vtrom the attaching arms ol' the pole pieces. Each flange is provided in its ends vvith the angularly disposed shoes 11 and 1Q respectively, the shoes of each pole piece projecting towards the shoes on the other pole piece and the opposed shoes being positioned in the same plane.

lThe pole shoes 11 and 12 embrace the cylindrical spool 13 Which is of a suitable nonmagnetic material and upon which the translating Wire coil lil is Wound. rlhe spool 13 has the usual cylindrical bore 15 open at its opposite ends. @ne edge of the permanent magnet 5 is engaged against the inner tace ot a front plate 16 also of a suitable non-magnetic material and to this plate the angular portion 9 oi' the pole piece G may be riveted or otherwise securely lined.

The mounting and arrangement oi the permanent magnet, the pole shoes and the translating coil constitute no part ot my present improvements and correspond tothe arrangenient disclosed in said issued patent. rlhe armature and its support which constitute the novel subject matter of the present improvements, are more particularly illustrated in a preferred embodiment thereof in Figures d and of the drawing to which reference may nony be had. The armature support 17 in a construction which I have found in practice to give the best results,

is of phosphor-bronze and is preferably of general cylindrical form. ln other Words, this support consists merely ot a cylindrical rod. rll`he diameter of this rod is determined by the diameter of the tubular armature 18. This armati'ire is ot sott iron and the bore 19 thereof is reduced in diameter at one ot 'its ends, as shown at 20. rlhe armature supporting rod llis of somewhat greater length than the length of the armature 18 and has a relatively long portion 21 oi? uniform diam- QQ, and an intermediate connecting portion The opposite sides ot the rod at the latter portion thereof are cut away or concave, as indicated at 24, thereby providing midway between the portions 21 and 22, a relatively thin section constituting the 'lulerum 25 for the a "mature From this fulcruni pointthc portion 23 ot the rod gradually increases in thickness to the portions 21 and 22 thereof.

The. end portion 22 et the supporting rod 17 is of such dia-meter that it has a tight trictional lit in the reduced end 2O oli' the armature bore, as clearly shown in Fig. el of the drawings, While the longer end portion 21 ot yhe rod is normally concentrically spaced 'from the surface of the main section ot the bore 19. T he extremity ot this longer portion Q1 of the tulcruui rod which extends beyond one end ot the tubular armature is rigidly fixed or clamped in the end of a post 26 1which is suitably mounted on the lrontplate 16.

its also illustrated in Figure l of the drawing, the opposite ends of the tubular armature 13 project beyond the ends of the spool bore and are disposed between the complementary opposed shoes oi:l the pole pieces and i" ot' the permanent magnet. rl`he end portion 2:2 ot the vibratory tulcrum rod or 'support 1T for the armature is formed with a longitudinally extending lug 27 projecting beyond the end of the armature and to said lug one end of the rod QS is pivotally connected. This rod at its other end is adjustably connected as at 29 to the center of a diaphragm 30. This diaphramn may be constructed ot any suitable material now generally employed for this purpose, though l preferably use a diaphragm principally constructed of celluloid and 'from which l have found a maximum amplitude ot movement may be obtained in the vibratory mov ments of the magnet armature. ilowever, l do not claim such a diaphragm in the present application, as it constitutes the subject matter ot an independent invent-ion which l havedescribed and claimed in a (zo-pending application for patent i'iled March 23, 1923, Serial No. (527,063.

From reference to Figure 1 oi' the drawing, it will be understood that suitable binding posts are mounted on the front plate 16 and insulated from each other to which the ends of the magnet translating coil and the Wires ot' the telephonie receiving circuit are respectively connected.

The magnetic structure above described is enclosed Within a casing 31 of hard rubber or other suitable material which is eX- tcriorly threaded at one end to receive the usual ear piece 32 having a central opening therein through which the sounds caused by vibration ot the diaphragn'i 30' are disseminated.

ln the operation oit the telephone instrumeut above described, it will be understood that the alternating currents coming in over the line are translated by the electromagnetic coil and as long as the magnetic flux oli the polel pieces is equal. the tubular armature and its fulcrum support will remain in a normal position in coinciding atrial relation` to the bore ot the coil spool. rl`he passage ot :fluctuating voice currents over the receiving circuit causes changes in direction and strength of the magnetic flux in accordance With the variations in t-he voice currents and thus produces a corresponding variation in the attraction and repulsion of the armature relative to the pole shoes. The relatively thin intermediate section 23 oit the armature support possesses such inherent resiliency that the end portion 22 of said support is causer to vibrate when the opposite ends of the tubular armature are acted upon by the variations in strength of the magnetic currents, as above explained. rEhe center of such vibratory movements is at the fulcruin 25, which fulcrum, it will be observed, is located exactly midway between the ends of the tubular armature and precisely in line `with its axis. Therefore, it is apparent that in the vibration of the end portion of the support l?, the tubular armature moves therewith and the extent of movement of this end of the support and the corresponding end of the armature in one direction is exactly equaled by the extent of mover-nent of the opposite end of the armature in the other direction. Thus, while the ,armature may freely vibrate in the bore of the coil spool, such vibration takes place from point centrally located in the line of the armature axis so that the vibrating movement which is transmitted through he rod 28 to the diaphragm is caused solely by the fluctuating voice currents and there is no false movement produced owing to the loc( tion of lthe fulcrum point of the armature or other mechanical influences which to some extent, would modify the accurate reproduction of the voice currents in the form of sound tones. ln other words, l have found that by thus mounting the armature so as to insure a correct viliratory movement thereof from a fulcrum located at the geometrical center of its structure so that the movements of the armature ends in opposite directions under the influence of the magnetic flux are exactly equalized, there is secured a very loud and remarkably clear reproduction of t-he voice currents in the form of sound. lit will he appreciated that this new mounting for the armature is exceedingly simple, and that the production cost thereof and consequently, the selling price of the instrument in which the magnetic structure is embodied, will be materially less than that of similar instruments now in general use and which are of relatively complicated construction.

ln Figure (S of the drawing l have illustrated another possible form of the vibratcry armature support in which the rod 1? has an intermediate reduced cylindrical section 23, the centra-l part of which is of minimum diameter and constitutes the fulcrum point or center of vibration of the arma ture. lt may also be possible in certain instances to employ an armature support 17, as shown in Figure 7, which is of uniform diameter throughoutits length. lt is of course, understood that the point of fulcrum of an armature of this form would be determined by its length and the distance from its fixed end enteriorly of the coil spool to Adie point at which the other end of the support is fixed in the armature, and that of course the strength of the magnetic currents and the inherent resiliency in the structure of the armature support would be accurately predetermined. However, for most practical purposes in the small powered radio receiving set, l have found the armature mounting as shown in Figures l. and 5 of the drawing, admirably answers the desired purpose.

llhile primarily, the present invention is designed for use as a telephone receiver, it is obvious that the instrui'nent might also be used as a transmitter, since when tl e sound waves of the voice are impressed upon the diaphragm, the vibration of the latter causes a movement of tie armature. rhis produces electrical impulses in the coil which will be transmitted over the line.

have herein shown and described a construction of my improved telephone apparatus which in actual operation has been found entirely practical. lt is possible, however, that in certain comn'iercial adaptations of my present improvements it may be found desirable or necessary to resort to certain mechanical changes in the form and construction of the armature or its vibratory support. Accordingly, it is to be understood that l do not desire to be limited to the precise details to which l have herein referred, but reserve the privilege of adopting all such legitimate changes in die form, construction and relative arrangements of the several parts as may be fairly embodied within the spirit and scope of the invention as claimed.

l claim:

l. An armature for i'uagnet telephones, and resilient fulcrum means for said armature having the physical and geometrical fulcrum axis thereof intersecting the longitudinal axis of said armature.

2. In telephonie apparatus, a tubular magnet armature and a vibratory support coaxially positioned through said arl'uature and having a fulcrum located within the bore of said tubular armature.

3. ln telephonie apparatus, a tubular armature and a support extending longitudinally through the armature and having a vibratory part fixed to the armature and provided with a fulcrum located midway between the ends of the armature.

4f. In telephonie apparatus, a tubular armature and a support extending longitudinally through the armature and having a vibratcry part fixed to the armature and provided with a fulcrum located midway between the ends of the armature and in the line of its axis.

5. ln telephonie apparatus, a magnet coil, an armature extending through the bore of said coil, and a vibratory support for the armature having a part of its structure formed to provide a iinlcruin centrally positioned between the ends ot the armature and intersecting ythe axis thereot..

G. In telephonie apparatus, a magnet armature, a support for said armature lined at one ot' its ends in spaced relation to the armature and' having a vibratoiy part con nected to the armature, said vibratory part having a ulcruni positioned midvfay between the ends of the armature and intersecting the axis thereol?.

7. An armature for magnetic telephones and fulcrum means therefor, said means and the armature having coacting parts retaining the fulcrum means and armature inassembled relation for arrangement as a unit in operative relation to the telephone magnet, said means having a ful/rum centrally positioned between the ends oi the armature and in line with the axis thereof, and supporting said arn'iatnre tor vibratory movement relative to the telephone magnet. 8. A tubular armature ttor magnet tele phones, and a itulcrum member for the armature fixed in one end of the armature bore to normally support the armature in neutral position i'or vibratory movement between the magnet poles, said support extending through the armature and fixed at its other end independently of the armature and having a ulcrum located centrally between the ends oit' the armature and intersecting the axis thereof.

9. A tubular armature for magnet telephones, and avibratory supporting rod fixed in one end of the bore oit the armature and extending longitudinally therethrough, means for ixedly securing the rod at its other end, said rod having a reduced intermediate section providing ay fulorum located centrally between the ends of the armature bore and intersecting the axis thereof.

10. In telephonie apparatus, a tubular armature and a ulcrum member supporting said armature for oscillatory vibration and resaca@ having part fixed Within the bore, of the armature t'or vibration withk respect to av tulcrumy located intel-mediate the ends of the armature.

il. In telephonie apparatus, a tubular armature and a support for said armature consisting ot a' rod having a vibratory end portion trictionally engaged with the Wall et the armature bore and having its i'ulcrum intersecting the longitudinal axis ot' the armature.

l2. In telephonie apparatus, a tubular armature, a supporting member fixed at one of its ends and having a vibratory portion normally coaxially related with said armature, and fixed Within one end of the armature bore.

13. In telephonie apparatus, a tubular armature, supporting means therefor including a part secured in fixed relation to the armature exteriorly or the armature bore and a vilnatory part extending within and closing one end ot the bore of the armature and having a itrictional connection with the Wall thereof.

l-t. In telephonie apparatus, a tubular a-rmaturel having one end of its bore of reduced diameter, a supporting member for said armature extending through the bore thereof having a part normally spaced concentrically tromthe wall of the armature, and another vibratory part oi said member being fixed within the reduced end ot the armature bore. p

l5. In telephonie apparatus, a tubular armature havingI one end oii its bore oli' reduced diameter, a rod extending through said armature` and having a vibratory end portion fixed in the reduced end of the armature bore, the Wall ot the armature for the remainder ot its length being norniially con centrically spaced iirom said rod.

In testimony that I claim the foregoing as my invention, I have signed my name hereun der.`

LAMBERT SCHMIDT. 

